What we know and don't know about climate change (3)

Since the beginning of the industrial age in the 19th century, CO2 levels in the atmosphere have increased from 280 parts per million (ppm) to 380 ppm. Satellite measurements now show both that less infrared of the specific frequencies absorbed by CO2 and other greenhouses gases is escaping the planet and that more infrared of the same frequencies is being reflected back to Earth's surface. While many factors affect our planet's climate, there is overwhelming evidence that CO2 is the prime cause of its recent warming."

However, there is a lot we still don't know. For example, the biggest unknown is how humanity will respond to the diagnosis that our Earth is sick and needs us to immediately change. When our physician tells us our health depends on whether we take care of it or not, she is speaking a simple, basic truth.

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